1. Field of the Invention
The instant invention relates to the development of a method for manufacturing an overhead multipurpose cable for outside telecommunication, of Voice, Video, and Data Distribution (VVDD) type, longitudinally and externally reinforced with a support vein, permitting the obtainment of a telephone cable with larger bandwidth levels of operation, and conserving the operation frequencies for voice transmission.
2. Previous Art
The communication cables for interior use based on metal conductors, with polyolefin insulation, formed in pairs and without shielding insulating them against electromagnetic interferences have shown an ever faster development in such a way that today they can be used in frequency ranges of up to 250 MHz, according to US specifications Nema WC 66-99. The field of application of said cables has basically been the local area networks (LAN), houses, apartment buildings or industrial buildings, public buildings, intelligent buildings or schools. The growth of local area networks has caused that the users of digital services such as internet, video on demand, high definition television, teleconferences, voice and fax services, request telephone networks having the adequate flexibility to give said services with high quality and higher transmission speeds that the ones currently available in the outside plant telephone cables which have not evolved much with regard to technical changes.
Innovations regarding telecommunication cables are known. For example, U.S. Pat. No. 5,739,473 describes a flame retardant telecommunication cable for use in office buildings; said cable consists of a conductor array insulated in groups of twisted pairs and the insulation used in the core group is different from the insulation used in the surrounding groups, its main characteristic being the arrangement of its structure and the use of a fluorinated copolymer. U.S. Pat. No. 4,319,071 describes a telephone communication cable with a large number of pairs of small conductors, the main characteristic of which is a liquid filling based on waterproof paraffin oils.
The instant invention is an improvement on Mexican patent application PA/a/2000/006808, which relates to a multiple purpose telephone cable with operation levels of larger bandwidth, from 0 to 100 MHz together with the maintenance of operation frequencies for voice transmission.
The voice, video, and data distribution (VVDD) cables show an improvement with regard to the electromagnetic interference levels between adjacent pairs or between the sector or groups constituting the cable and multipair telecommunication cables are obtained with constructions that can include from 2 to 600 pairs.
The geometrical formation of the cables can vary depending on the final installation of said cables. Said installation can be directly underground or in telephone ducts in case of geometrically rounded cables.
The characteristics of the improved cable relate to its use, i.e., the cable is designed for overhead use and thus said cable does not have filling preventing moisture penetration such as gel materials or can contain swellable powder. Thus, it does not affect the efficiency of the conductance, capacitance or insulation resistance, and also relates to the self supporting capacity of the cable, related with the weight which depends on the number of the twisted pairs included in the cable design which is generally lower compared to the number of pairs for cables for ducts or underground purposes.
The overhead cable of the present invention provides higher current carrying capacity, i.e., maximum amount of electrical current a conductor can carry before sustaining immediate or progressive deterioration, as compared to underground cable. The current carrying capacity depends on several factors such as insulation temperature rating, electrical resistance, frequency of current, ambient temperature and ability to dissipate heat. Overhead cables have higher current carrying capacity because heat can dissipate into the air, and wind can improve the rate of thermal dissipation.